The present invention is in the field of portable, motor driven vacuum p-umps having a movable working member which is motivated by electricity or a magnetic field. More specifically, the present invention relates to a personally portable, low negative pressure, motor driven vacuum pump having an electric power storage means and a moisture trap.
A number of portable, low pressure vacuum apparatuses capable of producing vacuum pressures down to about 500 mm HG currently exist. Medicine, particularly the wound healing arts, is a field where such devices have a specific utility. In the wound healing arts, it has been recognized that the removal of excess fluid from a wound site can improve the healing of the wound. This recognition has motivated the field to develop wound treatment regimens that include the use of vacuum devices for removing excess exudate from a wound site. For example, in full thickness dermal wounds devices to assist in the removal of excess fluid from these wounds have been developed and used. Further, because of the recognized benefits of encouraging patients to be active and mobile if possible, these devices need to be portable, and preferably, personally portable.
One strategy for providing a personally portable, low pressure vacuum source for drainage of wound site involves the use of a passive vacuum reservoir. Examples of this types of device includes those disclosed by Fell, U.S. Pat. No. 5,073,172; Seddon et al., U.S. Pat. No. 6,024,7311 and Dixon et al., U.S. Pat. No. 5,944,703. Typically, these devices comprise an evacuated cannister attached to a drainage tube. Because the vacuum pressure in the reservoir of these devices continuously decreases as the wound is drained (and the reservoir filled), they often include a means for regulating the pressure delivered to the wound site at some level below the maximum pressure of the vacuum reservoir. Additionally, these devices require a reservoir of a relatively larger volume than that of the volume of fluid they are capable of removing from a wound site.
Recognizing these limitations, the field has been further motivated to develop means for providing a portable, low pressure vacuum source for drainage of a user""s wound site which provides a relatively constant vacuum pressure. A strategy for accomplishing this objective includes having the device comprise a vacuum pump to provide a constant low pressure vacuum source, or to replenish a separate vacuum reservoir. An example of this type of device includes that disclosed by McNeil et al., U.S. Pat. No. 4,710,165. Also see U.S. Pat. No. 5,134,994 to Say. Although portable, these devices are bulky and obvious to an observer of the user, and may subject the user to embarrassment or personal questions. It would be beneficial to have a portable vacuum device that was personally portable by the user without being obvious to an observer.
An apparatus which addresses this latter benefit is disclosed in U.S. Pat. No. 6,142,892 to Hunt et al. The Hunt apparatus is supported on a belt or harness worn by the user, and is small enough to be unobtrusive when worn under a jacket or the like. However, the Hunt apparatus utilizes a liquid reservoir containing the fluids drained from a wound site. Fluids contained in the liquid reservoir of Hunt are subject to slouching, which may adversely affect the function of the Hunt apparatus if the fluid prematurely enters an inappropriate pathway (the outlet end of the cannister). Also, the Hunt device requires multiple tubes or a multi-lumen tube running from the device to the wound site to accomplish its full utility. Additionally, the Hunt apparatus is intended to be worn by a patient at waist level or higher. This means that wound sites below and distal to the users waist can be subjected to a higher vacuum pressure than with a device that may be located more proximal the wound site than the Hunt apparatus.
Although the above apparatuses may be useful in the field for accomplishing their intended purposes, it would be beneficial to have an alternative personally portable vacuum device that can be worn unobtrusively by the user, and which is not subject to slouching of the fluid it retains, and further which does not require special tubing to connect it to a wound site.
The present desiccator is a personally portable vacuum pump and moisture trapping device. The invention is useful where a user desires to carry a device for collecting and trapping small volumes of liquids. As a specific example, the present invention is therapeutically useful to provide a personally portable low negative pressure source and trap for aspirating and collecting fluid exudate from a wound or incision. A further benefit of the present invention for such applications involving biological waste is that the trap and all other components of the desiccator device that contact the aspirated biological materials are removable from the device and are replaceable. The desiccator device includes a trap, a vacuum pump head member, an electric motive mechanism and an electric control and power circuit.
The trap comprises a desiccator cartridge enclosing an interior space or chamber. An inlet port and an outlet port provide gas/liquid flow communication with the interior chamber of the desiccator cartridge. The desiccator cartridge is of a design and construction to withstand the application of an appropriate vacuum without substantial collapse of the interior chamber. Some distortion of the cartridge while under vacuum is desirable in some applications, e.g., where buffering of the vacuum pressure of the system is beneficial. A trapping agent is contained within the interior chamber for retaining the fluid that enter the chamber. The composition of the trapping agent is selectable by one of ordinary skill in the art in view of the teaching herein and in consideration of the characteristics of the fluid to be trapped.
A vacuum pump member or pump head is connected in gas flow communication with the interior chamber of the trap by having the low pressure port of the vacuum pump member being connected to the outlet port of the trap. The exhaust port of the vacuum pump member is vented to atmosphere. Operation of the vacuum pump member develops a low vacuum pressure which is communicated to the interior chamber of the desiccator cartridge and then to the inlet port of the trap. The vacuum pressure at the inlet port of the trap is selectable by the ordinary skilled artisan depending on the intended use of the present device. Typically, the selected vacuum pressures range less than about 250 mm Hg, and in part depends on the vacuum pressure to be delivered to the wound site and the any loss of vacuum pressure across the delivery tube connecting the inlet port to the wound site. An electric motive means (an electric motor) is coupled to the vacuum pump member and drives the pump head. An electrical control circuit, including an electrical power source, is in electrical communication with the electric motive means. The control circuit is operable to control the operation of the electric motive means.
The desiccator cartridge of the trap has only a single, ingress gas/liquid flow pathway, which is the inlet port. Additionally, the flow path at the inlet port is unidirectional, in that gas/liquid flow can enter the trap via the inlet port, but not exit or back flow out of the trap via the inlet port. Optionally, the personally portable vacuum desiccator includes a single passage gas/liquid flow path delivery tube for connecting the trap to a source of gas or liquids to be delivered into the trap. The delivery tube has an input end for communicating with the gas/liquid source and an output end connectable to the inlet port of the desiccator cartridge. A one-way valve is located proximate the inlet port of the desiccator cartridge. The one-way valve prevents the contents of the desiccator cartridge from back-flowing out of the inlet port. The one way valve may be separate from or incorporated into the inlet port. The desiccator cartridge is removable from the vacuum desiccator and separately disposable. A fresh desiccator cartridge is installed in the desiccator to replace the removed cartridge.
The desiccator cartridge contains a trapping agent for containing the liquids or moisture delivered to the trap under the force of the vacuum. The trapping agent combines with the liquid or moisture to alter its physical features, i.e., from a liquid or vapor to a mixed phase or solid state. Compositions suitable for use as trapping agents in the present invention are selectable by one of ordinary skill in the art in view of the present disclosure and teachings herein. The trapping agent should adsorb, absorb or in some way combine with the liquid or moisture to immobilize and keep it from sloshing in the desiccator cartridge as it is accumulated in the interior chamber. Examples of potentially suitable trapping agents include: a desiccant, an adsorbent and an absorbent. Specific examples include silica gel, sodium polyacrylate, potassium polyacrylamide and related compounds. Such moisture trapping materials are often found in disposable baby diapers and in feminine napkins. The level of moisture in the desiccant chamber is monitored by the moisture sensor circuit. When the amount of moisture trapped in desiccant material approaches saturation, the chamber may either be removed and disposed of or recharged with fresh desiccant material and repositioned in the device (depending on the design of the desiccator cartridge).
The present vacuum desiccator can further comprise a filter for blocking bacteria and/or untrapped moisture from passing into the vacuum pump member or from being vented to atmosphere. The filter may be located proximate the outlet port to protect the pump member and/or proximate the exhaust port to prevent venting bacteria or moisture to atmosphere.
The electric motive means of the vacuum desiccator includes an electric motor. The motor is coupled to the vacuum pump member to drive the pump. The motor may be coupled to the pump head by any of a number of means known to and practicable by the ordinary skilled artisan. For example, the motor shaft may be integrated with the vacuum pump head, it may be mechanically coupled to the vacuum pump so as to be readily separable from the pump head, or it may be magnetically coupled to the pump head so as to, again, be readily separable from the vacuum pump member. A readily separable motive means is particularly useful where the vacuum pump member and the desiccator cartridge are integrated together as a unit.
A purpose of the electrical control circuit is to monitor the condition of the device and to control operation of the motive means. The electrical control circuit includes the electrical power source for the device. The power source comprises an electrical power storage means, such as a battery. A feature of the power source is that the electrical storage means is removable from the electrical control circuit and is replaceable. Additionally, the electric control circuit optionally includes other ancillary circuits for the operation and control of the device. These circuits include: a moisture sensor circuit for detecting the presence of moisture proximate the low pressure port of the vacuum pump member; a timer circuit for intermittently operating the electric motive means; a vacuum pressure sensor circuit for detecting a vacuum pressure in the interior chamber or elsewhere in the device; and a pressure differential sensor circuit for sensing a difference in pressure between the inlet and outlet ports of the desiccator cartridge.
The component parts of the vacuum desiccator device which are in gas/liquid flow communication are replaceable. This allows the components of the device which are exposed to contact with the wound fluids to be separable from the other components of the device to facilitate cleaning or disposal of contaminated components.
The present personally portable vacuum desiccator can further comprise a housing for containing some or all of the component parts of the device. For example, the housing may contain the electric motive means and the electrical control circuit, while the other components are simply attached to the housing, e.g., an integrated pump head/trap combination assembly. Other configurations obviously are possible, such as a housing containing the electric motive means and the electrical control circuit and additionally either or both of the trap (desiccator cartridge) and the vacuum pump member.
Additionally, the present vacuum desiccator device may comprise the battery being housed in a battery compartment attached or integral to the desiccator cartridge of the moisture trap. In this configuration, the battery and the desiccator cartridge are replaceable in the device as a single unit.
It is a feature of the present invention that the personally portable vacuum desiccator can be used as part of a treatment regimen to promote wound healing by drawing excess wound exudate away from the wound site. As an example of using the desiccator for this purpose, an open, full thickness dermal wound is covered with an air tight dressing, such as are commercially available. The input end of the gas/liquid flow delivery tube is positioned under the dressing in flow communication with the wound site. The vacuum desiccator is activated, a low negative pressure is produced at the wound site via the delivery tube and excess fluids excreted by the wound are removed under the force of the low negative pressure.